DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage. Cadillac Eldorado 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage

Engine Controls Component Views
MAF Sensor, EVAP Components and EGR Valve
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The intake air temperature (IAT) sensor is a thermistor (a variable resistor) that measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit through a pull-up resistor. When the intake air is cold, the PCM detects a high voltage on the IAT signal circuit. As the intake air warms, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittently low IAT signal voltage (high temperature indicated), DTC P1112 will set.

Conditions for Running the DTC

•	No ECT sensor, or VSS DTCs are set.

•	Engine coolant temperature is less than 100°C (212°F).

•	Vehicle speed is greater than 15 km/h (9 mph).

•	Engine run time is greater than 10 seconds.

Conditions for Setting the DTC

•	The IAT sensor signal voltage is less than 0.08 volts (approximately 133°C (271°F)).

•	The condition exists for less than 5 second.

Action Taken When the DTC Sets

•	The PCM will illuminate the malfunction indicator lamp (MIL) the first time the malfunction is detected.

•	The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed.

•	The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

Step

Action

Value(s)

Yes

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Are any other DTCs also set?

Go to the other DTCs first

Go to Step 3

Test the IAT sensor signal circuit for the following intermittent condition(s):

•	Short to chassis ground

•	Short to the IAT sensor ground

If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 4

Go to Diagnostic Aids

Turn ON the ignition.
Review and record the scan tool Fail Records data.
Clear the DTCs.
Operate the vehicle within the parameters listed in the Conditions for Running the DTC.
With the scan tool, monitor the Specified DTC Information for DTC P1112.

Does the scan tool indicate that DTC P1112 passed?

System OK

Go to Step 2